BAS Australia 2026: Complete Guide for eCommerce & Small Business Owners

If you run an online store, freelance business, or small-to-medium company in Australia and you’re registered for GST — BAS is part of your life. This guide breaks down everything you need to know, with specific detail for eCommerce sellers, sole traders, and growing SMEs.

What Is a Business Activity Statement (BAS)?

A Business Activity Statement (BAS) is a form you lodge with the Australian Taxation Office (ATO) to report your business taxes and make any required payments for a specific period. In short, it gives the ATO a clear snapshot of your business’s tax position.

It mainly captures:

• The GST you’ve collected from customers
• The GST you’ve paid on business expenses

Depending on your business, your BAS may also include:

• PAYG withholding: tax deducted from employee wages
• PAYG instalments: advance payments toward your income tax
• Fringe Benefits Tax (FBT) instalments: if applicable
• Other taxes such as luxury car tax or wine equalisation tax

Who Needs to Lodge a BAS?

You are required to lodge a BAS if your business is registered for GST. If you’re not GST-registered, you won’t need to lodge a BAS — though you may still need to submit an Instalment Activity Statement (IAS) if you have PAYG obligations.

When do you need to register for GST?

You must register for GST once your annual business turnover is expected to reach $75,000 or more (or $150,000 for non-profit organisations) within 12 months.

Compulsory registration regardless of turnover applies to:

• Taxi and ride-sourcing services (including rideshare platforms)
• Businesses claiming fuel tax credits

eCommerce & Online Sellers – If you sell through Shopify, Amazon, eBay, Etsy, or any subscription platform, your revenue can scale past $75,000 faster than you expect. Many online sellers hit the GST threshold mid-year without realising it, which can trigger backdated liabilities. Monitor your rolling 12-month turnover regularly — or let Infinity22’s eCommerce bookkeeping service track it for you.

BAS Lodgement Frequency and Due Dates

The frequency of your BAS depends on your annual turnover:

Annual Turnover	Lodgement Frequency
Under $75,000 (voluntary GST registration)	Annually
$75,000 – $20 million	Quarterly
Over $20 million	Monthly

Most small businesses and sole traders fall into the quarterly category — 4 lodgements per year.

Quarterly BAS due dates

Quarter	Period	Due Date
Q1	July – September	28 October
Q2	October – December	28 February
Q3	January – March	28 April
Q4	April – June	28 July

For monthly lodgers, the BAS is due within 21 days after the end of each month. For annual lodgers, the deadline is typically 31 October.

Important – Due dates shift when they fall on weekends or public holidays, and the ATO updates them annually. Always confirm current deadlines at ato.gov.au or with your registered tax agent. Missing a deadline can result in Failure to Lodge (FTL) penalties starting at $313 per 28-day period overdue.

How to Prepare Your BAS: What You’ll Need

Before sitting down to fill out your BAS, gather the following:

• Your Australian Business Number (ABN)
• Your GST accounting method: cash basis (report when money is received/paid) or accruals basis (report when the invoice is issued)
• Total sales for the reporting period, including GST-free and input-taxed sales
• Total GST collected from customers
• Total GST paid on business expenses (your input tax credits)
• PAYG withholding amounts (if you have employees)
• PAYG instalment amount (if applicable)

GST Collected − GST Paid = Net GST to pay (or refund)

If you’ve paid more GST on business expenses than you’ve collected from customers, you may be entitled to a GST refund from the ATO — a situation common for eCommerce businesses with high inventory or software costs.

How to Lodge Your BAS

There are three main ways to lodge a BAS in Australia:

1. Online via myGov or the ATO Business Portal

The most common option for individuals and small business owners. Log in to your myGov account linked to the ATO, or use Online Services for Business. Sole traders use myGov; companies, trusts, and partnerships use Online Services for Business with a verified myGovID.

2. Through a Registered Tax Agent or BAS Agent

A registered agent can lodge on your behalf — often with an extended due date under the ATO Lodgment Program. This is the smartest option if your finances are complex, you sell across multiple platforms, or you simply don’t want to manage it yourself.

Infinity22 is a registered tax agent with the Tax Practitioners Board (TPB) — which means we are authorised to handle not just your BAS lodgement, but also your income tax returns and broader tax advisory. Unlike a BAS-only agent, a registered tax agent covers your entire compliance picture in one place. Get in touch to find out how we can help.

3. By Paper/Mail

The ATO will send a pre-printed BAS form if you’re set up for mail. It works, but it’s the slowest method and not recommended for most businesses.

Accounting Software Tip – Cloud-based tools like Xero, MYOB, and QuickBooks connect directly to the ATO via Standard Business Reporting (SBR) and can pre-populate your BAS figures from your transaction data. For eCommerce businesses processing high volumes of transactions — especially those syncing from Shopify or Amazon — this automation saves hours every quarter and significantly reduces errors.

How GST Works Inside Your BAS

GST (Goods and Services Tax) is a flat 10% tax on most goods and services in Australia. Your BAS is the mechanism that reconciles how much GST you’ve collected against how much you’ve paid — and determines whether you owe the ATO or are owed a refund.

Here’s a simple example:

• You invoice a client $1,100 (including $100 GST)
• You buy software for $220 (including $20 GST)
• Net GST to pay the ATO: $100 – $20 = $80

The GST you collect is a liability. The GST you pay on purchases is a credit. Your BAS reconciles the two.

Not all sales attract GST. GST-free supplies include most fresh food, some medical services, and certain education. Input-taxed supplies (such as financial services and residential rent) don’t attract GST but also don’t allow you to claim input tax credits. Getting these distinctions right on your BAS is critical — especially for online businesses selling a mix of taxable and exempt products.

PAYG Withholding and Instalments: How They Appear on Your BAS

Beyond GST, your BAS may also include PAYG (Pay As You Go) obligations. Two components can appear:

• PAYG Withholding: If you have employees, you’re required to withhold tax from their wages and remit it to the ATO. This is reported on your BAS.
• PAYG Instalments: If you’re a sole trader or business owner who earned above certain thresholds in the prior year, the ATO may require you to pre-pay income tax in quarterly instalments rather than a lump sum at year-end.

The ATO will notify you if you’ve been enrolled in PAYG instalments. Thresholds change periodically — check the ATO’s PAYG instalment page for current figures.

Not sure if your BAS is set up correctly? – BAS errors — wrong GST categories, missed PAYG amounts, incorrect accounting methods — are the #1 trigger for ATO audits. Infinity22 is a registered tax agent with the TPB, authorised to review and lodge BAS for eCommerce sellers, sole traders, and SMEs across Australia.

Common BAS Mistakes and How to Avoid Them

1. Claiming GST on non-eligible purchases

Not everything attracts GST. Fresh food, some healthcare services, and certain financial supplies are GST-free or input-taxed. Claiming credits on these items is incorrect and a common ATO audit trigger.

2. Mixing up cash and accruals reporting

Whatever GST accounting method you choose, stick to it consistently. Switching methods mid-period leads to double-counting or missed amounts.

3. Not keeping adequate records

Every figure on your BAS must be backed by documentation — invoices, receipts, and bank statements. The ATO can audit your BAS at any time. For online businesses with hundreds of transactions per quarter, integrated accounting software is essential.

4. Forgetting to lodge a nil BAS

If you’re registered for GST and had no transactions during a period, you must still lodge a nil BAS. Failing to do so triggers FTL penalties.

5. Lodging late

The ATO takes lodgement deadlines seriously. FTL penalties start at $313 for every 28-day period overdue (up to $1,565 per statement for small entities). If you can’t meet a deadline, contact the ATO or your tax agent before the due date to request an extension or payment arrangement.

6. Getting GST wrong on online platform sales

For businesses selling through Shopify, Amazon, Etsy, or SaaS subscription platforms — particularly those with international customers — GST treatment is nuanced. Some marketplace platforms remit GST on your behalf under the electronic distribution platform (EDP) rules; others don’t. Over- or under-reporting GST from platform sales is one of the most common errors Infinity22 sees in eCommerce BAS filings. If you’re unsure how your platform handles GST, speak to one of our eCommerce accountants.

Sound familiar? – These are the exact mistakes that trigger ATO reviews — and the exact situations Infinity22 resolves for eCommerce and small business clients every quarter. We don’t just lodge your BAS; we make sure it’s right.

BAS Preparation Checklist

The best way to ensure an accurate BAS is to maintain consistent bookkeeping throughout the reporting period — not scrambling at the end of the quarter.

Use this checklist every quarter:

• Reconcile your bank accounts regularly (weekly or fortnightly is ideal)
• Categorise income and expenses at the point of entry, not retrospectively
• Flag GST-exempt purchases correctly when they’re recorded
• Keep all source documents — invoices and receipts — organised and accessible
• Reconcile payroll records against your PAYG withholding before lodging
• Double-check totals before submitting — don’t accept software-generated figures without a sanity check
• Set calendar reminders 2 weeks before each BAS due date

Can You Fix a BAS After Lodging?

Yes. If you discover an error in a previously lodged BAS, you can revise it. Errors under $10,000 can usually be corrected on your next BAS. Larger corrections require a formal amendment submitted through the ATO’s online services or via your registered agent.

Do Sole Traders Need to Lodge a BAS?

Only if registered for GST. If your sole trader income is under $75,000 and you’re not GST-registered, no BAS is required. But once you’re registered — or you cross the threshold — BAS becomes mandatory, typically on a quarterly cycle.

Note that even as a sole trader, if you have PAYG withholding obligations (e.g. you pay wages to a contractor under a voluntary agreement) or are enrolled in PAYG instalments, you may still need to lodge an IAS or include PAYG on your BAS.

BAS Agent vs Tax Agent: Which Do You Need?

Under Australian law, these are two distinct registrations. A BAS agent is registered with the TPB specifically to prepare and lodge BAS and provide related bookkeeping advice. A tax agent holds a broader licence — they can handle everything a BAS agent can, plus income tax returns, tax planning, and advice across all federal tax laws.

Working with either type of registered agent has a practical benefit beyond accuracy: extended lodgement deadlines. If you’re managing BAS yourself, you’re locked to the ATO’s standard due dates. An agent’s lodgement program can give you additional time — particularly valuable at the end of the financial year.

Infinity22 is a registered tax agent with the Tax Practitioners Board (TPB) — meaning we can handle your BAS lodgement, income tax returns, and broader tax advisory all under one roof. You can verify our registration at any time on the TPB Public Register. We specialise in eCommerce businesses, SaaS companies, agencies, freelancers, and SMEs across Australia.

Let Infinity22 handle your BAS

As a registered tax agent with the TPB, Infinity22 can manage your BAS lodgement, income tax returns, and ongoing tax advisory — not just activity statements.

We specialise in eCommerce, SaaS, agencies, freelancers, and SMEs across Australia, and connect directly with Xero, MYOB, and QuickBooks to make compliance seamless.

Frequently Asked Questions